Calibration adjusting means



Patented Jan. 9, 1940 rATENT oFFIcE CALIBRATIO-N ADJUSTING MEANS Hans Linde and Arnold Soller, Michigan City, Ind.

Application Octoberv 12, 1936,` SerialNo. 105,279

' 4 Claims.

A further object is to provide means for adp justing the calibration of a shiftable member comprising resilient members applying opposed stresses to said shiftable member, and a single member associated therewith for adjusting the tension of both resilient members and thereby adjusting the position of the shiftable member. vA further object is to provide means for ad- "justing the calibration of the indicator mechanism of an instrument, comprising resilient members exerting opposed stresses on said mechanism and adjustable to approximate accuracy, and means for adjusting said indicator mechanism independently of said `resilient members for complete accuracy.

A further object is to provide adjusting means for effecting small adjustments of the indicator of an instrument independently of and relative to the actuating means thereof.

' Other objects will be apparent from ythe description and the appended claims.

In the drawing:

Fig.y l is a View of a combination draft and pressure gauge in front elevation.

Fig. 2 is a vertical longitudinal sectional View taken on line 22 of Fig. l, with certain additional parts being shown in section.

Fig. 3 is a fragmentary enlarged side View of the calibration adjusting means with parts shown in section.

Fig. ll is a fragmentary transverse vertical sectional View taken on line di-4 of Fig. 3. Fig. 5 is a fragmentary top plan view of the calibrationv adjusting means viewed in the direction of the arrow A in Fig. Fig. 6 is a longitudinal sectional view of a detail of the secondary adjusting means.

Referring to the drawing which illustrates one embodiment of the invention as applied to a combination draft and pressure gauge by way of illustration, the numeral Ill designates a housing having a sight opening in one face thereof closed by a transparent member I I. Behind this 'transparent member II a scale I2 of any suitable type is mounted in the housing, there preferably being a space provided between one side edge of the scale and the adjacent side wall of the hous- 5' ing as illustrated in Fig. 2for purposes tobe hereinafter set forth. The scale I2 may be translucent whereby a suitable light source I3 will facilitate reading thereof.

Within the housing I0, and preferably at the lo l bottom thereof, is xedly mounted a frame I4 which is provided with an angularly upwardly extending portion I5 at the end thereof adjacent the rear wall of the housing and which terminates in spaced angularly upwardly directed arms I6. On the frame I4 is mounted the casing of any suitable or desired instrument operating member I 1. As shown here for purposes of illustration, the operating member Il comprises a two-part casing i8 which mounts a slack leather ?0 or other suitable diaphragm I 9 therebetween. To the opposite sides of kthe central portion of diaphragm I9 are secured rigid plates 20 which iixedly carry a perpendicularly'extending rod 2l which .passes through an opening 22 in one part v2li of casing I8. The opening 22 is sufficiently large to open one side of the casing I8 to atmosphere and to accommodate lateral play of rod 2l under certain operating conditions. Ar suitable con'- nection 23 is provided in the part of casing I8 30 opposite that in which opening 22 is formed, and this connection mounts one end of a conduit or tube. 24 which is adapted for insertion in the chimney or draft line, or forconnection with a pressure source to be tested. Thus the chambers 35 of casing I8 on opposite sides of the diaphragm are respectively open to atmosphere and in communication with the member to be tested, but said opposed chambers are sealed from each other by the diaphragm.

In spaced relation to the opening 22 of casing I8 and adjacent the end of said casing opposite the frame portion I5, a standard 25 is fixedly carried by said casing. This standard pivotally mounts, at 25, the forward end of an elongated 45y rigid lever 21. Journaled in the upper ends of frame arms I6 is a shaft 28 which fixedly mounts a collar 29 adjacent the center thereof. Apointer arm 32 is xedly mounted. on shaft 28 and exy tends forwardlyrtherefrom and through the space 50 between the housing wall and the side `edge of scale I2. Pointer arm 32 terminates `in a horizontal laterally bent tip 33`positioned in front of scale I2 adjacent the indicia thereof and rearwardly of transparent closure Il. A threaded hooked or otherwise connected to a stationary position.

rod 34 is iixedly secured to the collar 29 at one of its ends and extends therefrom in diametrically opposed relation to pointer arm 32, and on this rod 34 is threaded a suitable knurled nut 35 which forms an adjustable counterweight for the pointer arm 32.

The lever 21 is preferably of angle section, including vertical flange 36 for reinforcing the same. To the ange 36, adjacent the free end of said lever, is hooked the lower end of a coil spring 3l. The upper end of said coil spring is member spaced above said lever, as the anchor arm 38 projecting from one of Vthe arms I5 of frame Ul. Suitable means, such as ear 39, carried by the lever 2 opposite and below the point of engagement of spring 3": with said lever afford means for connecting the upper end of a second coil spring 40 to said lever. The two coil springs are preferably aligned, and the lower end of coil spring ill is connected to suitable adjusting means. As here illustrated, this adjusting means comprises a member di which is slidably received and guided in a suitable opening in the base of frame lll. The member iii is provided with a threaded bore into which the inner end of an adjusting screw l2 extends, said screw being threaded through the adjacent wall of housing if! and terminating in a knurled head i3 positioned exteriorly of the housing. The upper end of member il includes a flange extension 411 to which the lower end of spring A@ is connected.

The two coil springs 3l and lill are as nearly identical as possible. Thus care is used in selecting and pairing these springs to match the same as to all characteristics thereof, i. e. length, kind and gauge of wire, tension or strength, etc. By positioning the anchor arm 38 from the sp-ring connection with lever 2, when the lever is in unactuated position, a distance approximately equal to the spacing between said lever and frame base id, the springs 3l and GS, in assuming equally tensioned opposing relation, will position the lever 2l held therebetween at substantially zero In other words, the springs, in acting against each other, position the lever 2'? in a neutral position when the lever is unactuated. However, should this neutral position be such that the pointer 32 does not indicate zero on scale l2, the position of member di connected with spring il may be adjusted by screw 42 to either increase or decrease the tension of both springs and at the same time adjust the neutral position of lever 2l in a manner to bring the pointer to desired neutral zero indicating position relative to the scale l2. When in neutral position, the springs 3l and it must obviously be sufiiciently tensioned to permit the recoil of either a sufficient extent to accommodate movement o lever 2l in either direction to the full extent required for pivoting of pointer arm 32 to the maximum reading on scale i2, without in any way interfering with such lever movement. In other words, the normal length of each spring must be slightly less than the spacing between its connection points when the lever is actuated for its full range in the mechanism. Upon release of this force, the

spring tensions again act solely against each other and equalize, so that the pointer arm 32 is returned to zero position by the neutral positioning of the lever. Of particular importance in this construction is the fact that the use of vopposed springs of the character mentioned insures return of the lever and pointer arm to exact neutral or Zero position. In this connection, it has been found that instruments heretofore manufactured wherein the pointer actuator is otherwise spring controlled and calibrated, as by mounting thereof on a leaf spring, have the disadvantage that the pointer arm does not return accurately to Zero position after use, and hence requires frequent adjustment of the calibrating spring. This is obviously avoided by the opposed spring arrangement above described. It will also be seen that if spring adjustment of the instant construction is required, the same is easy to eiiect by virtue of the position of theadjusting screw exteriorly of the instrument housing, and that the single `adjusting means serves to tension both springs equally regardless of the extent of lever and pointer adjustment required to effect neutral setting of the pointer at zero.

In order to' provide a degree of accuracy of pointer adjustment and calibration greater than is practical by the construction above described, a pointer actuating means is provided to constitute a secondary calibration adjuster. Such greater degree of accuracy may also be rendered necessary by inability to pair together springs of exactly identical characteristics, with resultant need for compensation for the differences in the springs. For this purpose a rod 5 is xedly mounted on shaft 28 and extends therefrom in substantially parallel relation to pointer arm 32. The free end portion of this rod is threaded to adjustably mount one part of suitable means for adjusting the position of the pointer arm relative to lever 21. As here illustrated, and best shown in Figs. 3 and 6, this adjusting means. may comprise a cylindrical thumb screw i6 threaded on rod 45 and having an enlarged knurled collarl M. On the cylindrical body of thumb screw 46 is rotatably mounted a sleeve $8 which is held in place against movement longitudinally of said screw by flange 19. A rod 50 is pivotally connected to sleeve 'i8 at its upper end which may be of forked shape if desired. At its lower end the rod 59 is hooked or otherwise connected to flange 36 of lever 2l at any selected one of several spaced holes i in said ilange. In the use of the device, assuming that approximate or close adjustment of the pointer arm has first been effected by means of screw 12, springs 3l, M and associated parts as above described, the position of thumbscrew d6 longitudinally of rod l5 is ad- .lusted By so doing, the angular relations of the rod 50 with respect to rod t5 and lever 2l are altered with resultant minute changes of spacing and angular position of said rod and pointer arm 32 relative to lever 2l. The leverl 27, being held in a neutral position by springs 37, lli?, remains stationary so that only the pointer and rod d5 are moved, and a very ne degree of adjustment results. It will be understood, of course, that the most accurate adjustment will result when the thumb screw 42 is adjusted before the secondary adjustment through thumb screw t5 is made. In other words, the adjustment of the pointer arm is best used only for those fine adjustments of pointer position which are impossible to obtain through thumb screw d2.

While only one embodiment of the invention Cil has been herein illustrated and described, it will be obvious that the invention may also be embodied in a large number of other instruments of `different types and constructions. In allsuch embodiments the Opposed tension springs calibrate the indicator actuating means, and the position of the indicator may be adjusted by a single control member. It is evident, however, that there may occur certain requirements which Will render necessary the use of opposed springs which are not equal, `as in length or tension, in which case the invention may nevertheless be employed by the use of springs which are selected for their required relative characteristics. It Will also be understood that other` embodiments than that here illustrated may also include the minute secondary adjustment of the indicator relative to the operating or actuating means thereof.V

We claim:

1. The combination with an instrument hav-y ing a housing, and an operating unit in said housing including a stationary frame, an indicator shiftabiy mounted yon said frame, a force re- 2.- The combination with an instrument havmeans,

ingl apivoted indicator andv actuating means ltherefor including a shiftable member and a` link pivoted to said lshiftable member. and-'connected to said indicator, of means for adjusting the normal position of said indicator and actuating member and including a pair of tension y springs acting on said member in opposed relation v and means for varying the tension of said springs,

' and means for shifting the .point of connection of said link and indicator to adjust the position` of said indicator yrelative to said member.

3. The combination with an instrument hav-I ing a Apivoted indicator, vpressure responsive a shiftable memberr actuable by said means and av link between said member and indicator, of a pair of tension' springs acting kon said member in opposedfrelation, means for ladjusting the tension of said springs to adjust the position of said member and indicator, and means for varyingl the normal angularposition of said A link to adjust the position,of'said'indicator relaj tive to said shiftable member.

4. The combination with an instrument hav- I t ing a pivoted indicator and actuating means in-l cluding` an elongated shiftable member having a `free end and a link between the` free end of said memberand said indicator, of means for calibrating said indicator comprising va pair of springs of substantially equal strength acting upon saidl member in opposed relation, means for adjusting the tension of said springs toadjust the normal v position of said indicator, and means for'adjusting. said link to compensate for inequalities in the strength of said springs.

' HANS LINDE.

ARNOLD SOLLER. 

